The invention relates to a manual sheet feeding mechanism adapted to feed sheets from a manual feeding tray into an apparatus on which the mechanism is installed. The invention relates in particular to a manual sheet feeding mechanism adapted for use in a sheet processing apparatus for processing certain processes to sheets, such as an image forming apparatus.
There are several sheet feeding methods used in such sheet processing apparatus. By the first method, sheets are fed from a sheet cassette provided in a sheet feeding section of such apparatus. By the second method, sheets are fed from a manual feeding tray provided in a manual sheet feeding mechanism that is mounted on a side wall of such apparatus.
The sheet cassette is used for storing a plurality of sheets of a size, often of a fixed size. Usually, sheets to be stored in the sheet cassette are ones that are frequently processed by such apparatus, e.g., plain paper sheets of standard size such as A4, A3, B4, or B5.
In contrast, the manual sheet feeding mechanism is used for feeding sheets that are less frequently processed, such as postcards, envelopes, and boards. The manual feeding tray has a placement surface on which guiding members are provided for positioning sheets along a perpendicular direction to a sheet feeding direction.
The guiding members are adapted to have contact with two respective side surfaces of the tray that are oriented parallel to the sheet feeding direction. The guiding members are slidable along the perpendicular direction so as to be adjustable to various sizes of sheets.
JP 2003-295733A discloses an image forming apparatus on a side wall on which a manual feeding tray is movably mounted. With no sheets to be placed thereon, the manual feeding tray is retractable to a position where a placement surface of the tray is oriented approximately parallel to the side wall.
However, projection of the guiding members from the placement surface requires a concavity in the side wall in which the guiding members are to be fitted, for proper retraction of the tray. This leads to problems with downsizing the apparatus as well as with simplifying an inner construction of the apparatus, as described below.
Since small-sized sheets such as postcards are sometimes placed on the manual feeding tray, the guiding members are arranged adjacent to the side wall of the apparatus. Inside the apparatus, on the other hand, sheet feeding devices such as a pick-up roller, sheet separating rollers, transporting rollers are arranged adjacent to the side wall for feeding and transporting sheets placed on the tray. Namely, the tray and the sheet feeding devices are arranged approximately in alignment on either side of the side wall.
Accordingly, the concavity requires the sheet feeding devices to be spaced from the side wall a sufficient distance to prevent the sheet feeding devices from having contact with the guiding members as fitted in the concavity when the tray is retracted. This causes the apparatus to be large in size. The concavity results in a relatively large distance between the tray and the sheet feeding devices. The concavity also requires a complex configuration such as to allow the pick-up roller to be arranged opposite an upper surface of sheet placed on the tray.
Also, since the guiding members are slidable on the placement surface of the tray along the perpendicular direction to the sheet feeding direction, it is impossible to specify an area of the side wall in which the guiding members are to be located when the tray is retracted in the apparatus. In order to ensure that the guiding members are prevented from having contact with the side wall when the tray is retracted in the apparatus, therefore, the concavity needs to be formed so as to cover the entire width of the side wall along the perpendicular direction to the sheet feeding direction. The concavity creates a large dead space inside the apparatus, thereby causing the apparatus to be large in size.
A feature of the invention is to provide a manual sheet feeding mechanism that has a manual feeding tray adapted to be prevented from having contact with devices provided in an apparatus on which the tray is mounted, when the tray is retracted in a side wall of the apparatus.
Another feature of the invention is to provide a manual sheet feeding mechanism with guiding members adapted to be retracted to such positions as to prevent an apparatus on which the tray is mounted from being large in size and complex in inner construction.